In order to grind a cam or bearing surface of a camshaft, it is standard to mount the camshaft in a lathe-like support that rotates the camshaft about the camshaft axis which is normally offset from the center of the cam. Abrasive tools, either in the form of abrasive stones directly engaging the cam surface or pusher heads pressing an abrasive band against the cam surface, are pressed generally radially of the axis against the cam surface to hone the surface, often with the addition of a cutting oil to cool the surface and carry off any particles. Since the cam center is offset from the cam axis, this requires the tools to move radially relative to the camshaft axis as they ride around the cam surface. It is also standard to relatively axially reciprocate the camshaft and the tools during such machining.
In the system described in commonly owned German patent 4,015,569 filed May 15, 1990 honing stones are mounted at the outer ends of long support levers whose inner ends are mounted at respective pivots having axes offset well away from and parallel to the camshaft axis. Biasing means engaged between the lever ends press the stones against the cam surface. Such a system has the disadvantage that the movement of the stones is along an arc, albeit a large one, so that the angle of attack of the stones on the surface changes somewhat as the radial spacing of the stone from the camshaft varies. In addition a relatively large mass comprised of the stone and the lever must be displaced in and out at a rate of speed depending on the rotation rate of the camshaft so that in regions where the stone must move radially out the inertia of the assembly increases the pressure exerted by the stone while in regions where the stone must move in rapidly the pressure is decreased. Thus the camshaft must be rotated slowly to reduce this effect, thereby reducing machining speed.
U.S. Pat. No. 4,993,191 of Judge shows another arrangement where two massive pivotal support arms each carry a pair of roller-type pushers that press an abrasive band against the camshaft surface. This system shares most of the disadvantages of the other above-described system.